/*
 * Copyright © 2015 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

/*
 * u_vector is a vector based queue for storing arbitrary
 * sized arrays of objects without using a linked list.
 */

#ifndef U_VECTOR_H
#define U_VECTOR_H

#include <stdint.h>
#include <stdlib.h>

#include "util/bitscan.h"
#include "util/macros.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Returns the smallest power of two >= x
 */
static inline unsigned util_next_power_of_two(unsigned x) {
#if defined(HAVE___BUILTIN_CLZ)
    if (x <= 1)
        return 1;

    return (1 << ((sizeof(unsigned) * 8) - __builtin_clz(x - 1)));
#else
    unsigned val = x;

    if (x <= 1)
        return 1;

    if (util_is_power_of_two_or_zero(x))
        return x;

    val--;
    val = (val >> 1) | val;
    val = (val >> 2) | val;
    val = (val >> 4) | val;
    val = (val >> 8) | val;
    val = (val >> 16) | val;
    val++;
    return val;
#endif
}

/* TODO - move to u_math.h - name it better etc */
static inline uint32_t u_align_u32(uint32_t v, uint32_t a) {
    assert(a != 0 && a == (a & -((int32_t) a)));
    return (v + a - 1) & ~(a - 1);
}

struct u_vector {
    uint32_t head;
    uint32_t tail;
    uint32_t element_size;
    uint32_t size;
    void *data;
};

int u_vector_init_pow2(struct u_vector *queue, uint32_t initial_element_count, uint32_t element_size);

void *u_vector_add(struct u_vector *queue);
void *u_vector_remove(struct u_vector *queue);

static inline int u_vector_init(struct u_vector *queue, uint32_t initial_element_count, uint32_t element_size) {
    initial_element_count = util_next_power_of_two(initial_element_count);
    element_size = util_next_power_of_two(element_size);
    return u_vector_init_pow2(queue, initial_element_count, element_size);
}

static inline int u_vector_length(struct u_vector *queue) {
    return (queue->head - queue->tail) / queue->element_size;
}

static inline void *u_vector_head(struct u_vector *vector) {
    assert(vector->tail < vector->head);
    return (void *) ((char *) vector->data + ((vector->head - vector->element_size) & (vector->size - 1)));
}

static inline void *u_vector_tail(struct u_vector *vector) {
    return (void *) ((char *) vector->data + (vector->tail & (vector->size - 1)));
}

static inline void u_vector_finish(struct u_vector *queue) {
    free(queue->data);
}

#ifdef __cplusplus
    #define u_vector_element_cast(elem) (decltype(elem))
#else
    #define u_vector_element_cast(elem) (void *)
#endif

#define u_vector_foreach(elem, queue)                                                                            \
    STATIC_ASSERT(__builtin_types_compatible_p(__typeof__(queue), struct u_vector *));                           \
    for (uint32_t __u_vector_offset = (queue)->tail;                                                             \
         elem = u_vector_element_cast(elem)((char *) (queue)->data + (__u_vector_offset & ((queue)->size - 1))), \
                  __u_vector_offset != (queue)->head;                                                            \
         __u_vector_offset += (queue)->element_size)

#ifdef __cplusplus
}
#endif

#endif
